What is a PDF?
PDF stands for Portable Document Format and is a creation of the Adobe Systems Corporation. PDF files originally acted as a bridge between printable documents and the files of instructions sent to printers in order to print the documents. The most common format used to tell printers what and how to print was another product of Adobe called PostScript. Yet, PostScript only describes the lines, curves and color fills that the printer should print, rather than the text of a document. This meant that PostScript files, while portable, were not suitable for maintaining document information in a manner which allowed for searching and copying text. PDF files are suitable for both purposes because they not only maintain the text of a given document but also its layout and presentation elements as well as other graphical objects such as pictures and charts.
PDF files are commonly used on web sites to allow people to download and potentially print out documents. This is primarily because Adobe has opted not to charge for their Acrobat Reader software, which can be run on all of the most commonly used operating systems. Additionally, the format itself can be freely used by non-Adobe software to export documents in the PDF format, making it easier to generate such documents. Given the lack of associated costs, the use of PDF files on the web has reached the point of ubiquity.
A number of software applications not affiliated with Adobe Systems may also be used to view PDF files, such as Apple's Preview software. However, because Adobe controls the standard, Adobe has generally extended the functionality supported by the format faster than support has been provided by third party software developers. This means that some of the more recent and advanced features of the PDF format, such as digital signatures, are often not supported by software applications not developed by Adobe Systems.
last updated 2009.10.14
